Print all the years dating back to when someone was born.

Sure, so what its doing is taking the age number, like 22, and counting all the way up to the current year, 2016. So 22, 23, 24 ... 2014 2015 2016. That's the numbers it was putting out.

I refactored it, to what I think you want.

$age = 22;
$yearsText = "";
for ($nYear = date('Y') - $age; $nYear <= date('Y'); $nYear++){ 
  $yearsText .= $nYear . ' ';
}
$yearsText = trim($yearsText);
echo $yearsText;

So basically we start out setting $nYear to the year the person was born, doing this by taking the current year, 2016, and minus their age, 22, so we get the year 1994.

Now, our loop runs as long as $nYear is less than the current year.

So when you run this, you should get 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Which is I think what you wanted? The last thing to do is to make $age be set dynamically by your form, but that's easy.